There are at least two general behavioral processes involved in concept learning, abstracting and relating (of relevant stimulus attributes). Two problem formats attribute identificaton (AI) and rule learning/identification (RL/I), have been developed to investigate and analyze these processes experimentally. The problems differ in terms of givens and unknowns: AI, rule given relevant attributes unknown; RL, attributes given, rule unknown. Conceptual rules differ in difficulty and affect the strategies used by Ss in AI. Experiments are planned to identify sources of rule difficulty, to test theoretical interpretations of the phenomenon, to explore conditions of training that reduce or eliminate the differences, and to describe any changes in strategic problem solving behavior which accompany rule learning.